SOTOP (Single Secure On-time Only Programmable) and SCSM (Single Circuit Secure Memory) are closely related circuits. Either or both may be used to create security devices with uncommon architectures that can provide for consumable keys (one-time keys as a limiting case, perpetual keys as the opposite) and high security. Such security devices are based on simplicity favored over ever-growing complexity. A hardware/microcode/firmware approach is used.
Extremely high security is possible at great (often unaffordable) cost using conventional software-based implementations as an alternative to the invention. Secure microprocessors have been abandoned in many applications such as cellphones—not for reason that their security is unneeded, but rather because their cost is prohibitive.
In any case, whether using previously developed solutions or the invention, adding a secure module to an insecure assembly will not automatically make the assembly secure. Rather a secure module merely provides the opportunity to design and build a secure assembly. Because the invention focuses on lowest cost rather than highest possible security it opens the door to low cost assemblies since, not only is the incorporated security module itself cheap but the cost of assembly features to accommodate it are low cost also.
One problem of using highly innovative solutions to meet commercial needs for superior security/cost tradeoffs is that because of the out-of-the-mainstream approach used unusual components have been needed and this augurs against very low cost until and unless extremely high volumes justify an ASIC (application-specific integrated circuit). Embodiments of the invention address that problem, and more.